METHOD FOR MAKING CURVED CORRUGATED SECTIONS WITH ADDITIONAL CORRUGATIONS ON HORIZONTAL WALLS OF MAIN CORRUGATIONS AND ON HORIZONTAL PARTS BETWEEN CORRUGATIONS Russian patent published in 1995 - IPC

FIELD: plastic metal working. SUBSTANCE: the first steps of the method involve shaping an intermediate profile with a preset pitch between main corrugations having excessive width of horizontal walls and bent side walls. Then width of horizontal walls of main corrugations is reduced to preset limit by curving them temporarily and bending the side walls of main corrugations to the preset angle, then, simultaneously with shaping of additional corrugations, the temporarily curved horizontal walls of main corrugations are straightened out with unchanged position of their side walls and intercorrugation distance. The width of horizontal walls of main corrugation on initially produced intermediate section is larger than their width on the finished section by the difference between 0.7 and 1.0 of the developed length of additional corrugation and its width while the side walls of main corrugations are bent to the angle ensuring this increased width. EFFECT: higher efficiency. 3 cl, 2 dwg